1. Field of the Invention
The present invention relates to underwater acoustics and more particularly to acoustic projectors. Even more particularly, the invention relates to an acoustic projector having increased mechanical strength by the addition of a metallic liner and/or a reinforced outer shell formed of epoxy graphite layers.
2. Brief Description of Prior Developments
In the deployment of low frequency underwater acoustic projectors effective management of mechanical stresses within the radiating device are a critical design issue that must be addressed to ensure successful operations over a wide range of depths and acoustic dynamic range. One of the stresses most difficult to manage is the z-axis stress or stress along the length of the projector. This stress is particularly difficult to manage when these devices use a filament wound composite shell component to serve as the primary mechanical structure within the radiating device.
The prior art method of slotted cylinder projector design was to concentrate on achieving high hoop modulus (circumference modulus) of a graphite/epoxy shell. In the winding process the manufacturer achieves high hoop modulus by having a wind angle, near 90 degrees, which reduced the z-axis modulus (in the length direction)
Having a reduced Z-axis modulus means the stiffness in the z-direction is reduced and thus during operation and depth excursion, the stress in that direction are increased. Not adhering to reduced dynamic range and depth could result in mechanical failure. For typical slotted cylinder projector operation and size limits, this increased stress reduces the depth and dynamic range capability of the slotted Cylinder projector.
A need, therefore, exists for an acoustic projector construction in which mechanical stresses are minimized so as to increase depth performance and dynamic range.